A project’s documented plan is the basis for
monitoring activities, communicating status, and taking corrective action.
Progress is primarily determined by comparing actual work product and task
attributes, effort, cost, and schedule to the plan at prescribed
milestones or control levels in the project schedule or WBS. Appropriate
visibility of progress enables timely corrective action to be taken when
performance deviates significantly from the plan. A deviation is
significant if, when left unresolved, it precludes the project from
meeting its objectives.

The term “project plan” is used throughout
these practices to refer to the overall plan for controlling the
project.

When actual status deviates significantly from
expected values, corrective actions are taken as appropriate. These
actions may require replanning, which may include revising the original
plan, establishing new agreements, or including additional mitigation
activities in the current
plan.